The present invention relates to an improved rare earth type magnet and a method for producing the same, and more particularly relates to production of high quality alloy magnet containing rare earth elements and well suited for use on electric and/or electronic appliances.
Conventionally, Fe-Al-Ni-Co-(Cu) type alnico magnets have been widely known in the field as alloy magnets of high quality. Despite the relatively high quality, use of alnico magnets in general connects to high production cost due to the content of expensive Co. In addition, advantages accruing from such high quality do not in practice outweigh disadvantages resulting from such high production cost. Like alnico magnets, production of Fe-Cr-Co type alloy magnets has recently been developed, which utilizes so-called spinodal transformation. Despite the higher quality than that of alnico magnets, the large content of Co in such type of alloy magnets again causes rise in production cost. Further, the quality of such type of alloy magnets is not high enough to fully suffice various demands on magnet quality increasingly raised in recent developments in the field of electronic engineering. In these circumstances, development of new alloy magnets of further advanced quality is strongly expected in the field.
Use of alloy magnets containing rare earth elements, in particular ferror-rare earth element type magnets, has recently been proposed. For example, an alloy magnet containing Fe and Gd and a metalloid element or elements such as B, has already been developed by use of a melt-casting method. When produced by the ordinary melt-casting method, however, the coercive force (iHc) of such a type of alloy magnet is in a range from 100 to 200 Oe and the magnetic susceptibility in a range from 15 to 30 emu/gr. The significantly lower levels of these magnetic characteristics disenable use of the alloy magnet of this type in practice.